Re: [hibernate-dev] Support for entities without default constructor

generation should be rather simple using ByteBuddy. Turns out that the ByteBuddy byte code provider already has an instantiation optimizer doing exactly that [1]. Unfortunately, though, from what I can say it's never used due to a bug in PojoEntityTuplizer which ignores the reflection optimizer's instantation optimizer. I've logged HHH-12284 [2] for that. --Gunnar [1] https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src... [2] https://hibernate.atlassian.net/browse/HHH-12284 2018-02-04 12:30 GMT+01:00 Gunnar Morling <gunnar(a)hibernate.org&gt;: > I like it, but I think that's two separate concerns: > > * using byte code generation to improve performance of entity > instantiations > * avoiding the need for entities to have a parameterless constructor, > emphasising the mandatory properties of an entity (by requiring them as > constructor parameters) and allowing read-only entities to be truly > immutable (i.e. with final fields) > > Both can be addressed independently. > > The latter seems more impactful for developer experience, the need for a > default constructor has been a long-standing point of criticism often > raised by DDD-minded folks. As said on Twitter, it'll likely require an > annotation to mark the "persistence constructor", i.e. the one to be called > by Hibernate in case there are multiple ones. And we need a mapping between > parameter names and entity property names. That's "for free" if parameter > names are part of the byte code as possible with the "-parameters" option > in javac 8, otherwise some help by the developer is needed. > > generation should be rather simple using ByteBuddy. > > --Gunnar > > 2018-02-04 8:34 GMT+01:00 Vlad Mihalcea <mihalcea.vlad(a)gmail.com&gt;: > >> For anyone interested, Josh Long tell more about why they took this >> approach where they inject the default constructor: >> >> https://twitter.com/starbuxman/status/960049941916696578 >> >> Rafael Winterhaler shows that this can be easily done with Byte Buddy >> which >> we already used before: >> >> https://twitter.com/rafaelcodes/status/959892398997458946 >> >> If we can prove that it's indeed significantly faster than using Java >> Reflection to build entities, >> I think we should think about taking this approach as well. >> >> What do you think of this? >> >> Vlad >> >> On Sat, Feb 3, 2018 at 5:03 PM, Vlad Mihalcea <mihalcea.vlad(a)gmail.com&gt; >> wrote: >> >> > Hi, >> > >> > I realized that we could allow users to define entities without a >> default >> > constructor. >> > >> > For Kotlin, which supportsdefault values, this could be beneficial. >> > >> > There is some info about how we could do that in this using Objenesis in >> > the following Spring issue: >> > >> > https://jira.spring.io/plugins/servlet/mobile#issue/SPR-10594 >> > >> > Let me know what you think, >> > Vlad >> > >> _______________________________________________ >> hibernate-dev mailing list >> hibernate-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/hibernate-dev >> > >